This invention relates to instrument transformers, and more particularly, to end caps for the primary winding of instrument transformers.
In many instrument transformers the core and coil members are molded in an electrical insulation material that forms both the insulation of the transformer and the exterior casing thereof. See, for example, U.S. Pat. No. 2,997,526. In these dry-type instrument transformers, often the primary winding if formed of one or more turns of copper or aluminum foil. This type of primary winding has led to two problems. One is the problem of the electrical stresses on the insultion which is caused by the sharp edges of the foil winding. The other is the tendency of the foil winding to collapse or become misshapened during the molding or encapsulation of the core and coil in the electrical insulation material.
It is, therefore, a primary object of this invention to provide a foil wound primary winding with a support means to give mechanical strength to such winding.
It is a further object of this invention to provide support means in the form of end caps for a foil wound primary winding, such end caps being provided with internal and external radii to relieve electrical stresses.